The disclosure relates to turbomachinery. More particularly, the disclosure relates to gas turbine engine airfoils and their designed vibrational responses.
Airfoils of turbine engine blades and vanes are subject to a number of performance-affecting conditions. The airfoils are subject to environmental exposure and thermal and mechanical loading. These factors are significant in each section of the engine for a variety of reasons. For example, in the fan section of high bypass engines, the airfoils have a large diameter with a relatively small thickness. In a high pressure compressor and in a turbine section, the airfoil is exposed to high temperatures. Cooling passages are provided in the turbine section airfoils, but such cooling passages are typically absent in the compressor section. For blades, rotational forces are also a significant dynamic stimulus.
Vibrational responses of the airfoil can provide an indication of how durable the airfoil will be during engine operation. If an airfoil operates too long at a resonant frequency during engine operation, the life of the airfoil may be significantly shortened as the airfoil is more highly stressed. An exemplary vibrational testing method is defined in United States Federal Aviation Administration (FAA) Advisory Circular 133.83-1 (Sep. 8, 2009). Designing airfoils with desirable resonant frequencies can prolong the useful life of engine components, particularly the airfoil itself.